Many military and commercial communication systems need compact low cost antennas such as aircraft and global positioning systems.
Microstrip antennas have been widely used instead of conventional antennas because they are relatively light in weight, low in cost, and have a low profile. Unfortunately, however, their bandwidth is too narrow for many applications, but there are some applications such as global positioning systems that require only a few distinct frequency bands rather than a continuous spectrum. The generally planar dual band antennas presently known have features perpendicular to the main plane of the antenna that are expensive to manufacture. These antennas have a ground plane on one side of a dielectric layer and patches of conductive material on the other.